jQuery upload file using jQuery's ajax method (without plugins)

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温柔的废话 2021-02-01 23:41
At moment I want to implement picture upload without using any plug-ins.
My upload form looks like this

      
      
        
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                   庸人自扰
                                             
                
                
                (楼主)
            
              
              
                2021-02-02 00:18
              

            
            
                        
AJAX or more appropriately XMLHttpRequest does not support file uploads yet. There are workarounds such as uploading through an </code>, but its rather cumbersome. Your time will be better spent in building your applications rather than reinventing these solutions. </p>

<p>But if you're curios as to how it works internally, then feel free to checkout the source code of some of the plugins that offer this functionality. A very simple explanation can be found at this link - http://www.openjs.com/articles/ajax/ajax_file_upload/</p>

<p>Basically, you change the form <code>target</code> to submit inside an <code><iframe></code>, thus avoiding the page refresh, and simulating AJAX, which it isn't really, but who cares - the end user can't tell.</p>

<p>A minimal example for an iframe based upload may look like this:</p>

<pre><code>$("#upComplete").click(function() {
    // create a dynamic iframe, or use existing one 
    var iframe = $("<iframe id='f' name='f' src=''>");
    // attach a load event to handle response/ know about completion
    iframe.load(function() { alert('complete'); });
    iframe.appendTo('body');
    // change form's target to the iframe (this is what simulates ajax)
    $('#uploadForm').attr('target', 'f');
    $('#uploadForm').submit();
});
</code></pre>

<p>Note that this does not do any response handling, but just sends the picture to the server. To handle the response, a callback must be written for the iframe's <code>load</code> event.</p>
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